SD Based boot volume?

[SubnetMask]

I've done some searching, with the latest thread I saw being from 2017, and the general consensus was that using SD cards isn't recommended. The two reasons I've seen mentioned are performance and reliability. As far as performance, how fast does the boot volume really need to be? If USB sticks will work, I'd think modern SD cards should be plenty fast enough. In terms of reliability, SD cards are generally quite reliable, except in high write situations, where they can use up their write endurance pretty quick - I've killed more than one or two that way in Raspberry Pi setups. But these days there's an answer to that: Sandisk High Endurance and Max Endurance cards. Take the 64GB Variants - the High endurance is rated for 5,000 hours of full HD recording and the Max Endurance is rated at 30,000 hours - Somehow I doubt FreeNAS/TrueNAS would come even close to writing that much to the boot media.

What is the thought of the experts with the introduction of these high endurance SD cards since the last thread I saw that was from before these cards existed?

 

[danb35]

If USB sticks will work

They'll work, but they're strongly discouraged--and I think that's going to be the general answer for SD cards as well, for pretty much the same reasons.

 

[HoneyBadger]

Purely from an endurance argument, Sandisk claims a 26Mbps bitrate, or 3.25MB/s - extrapolating that out and using the 30,000 hour lifespan of the Max Endurance card, that means about 351GB of lifetime writes. However, that's for a sequential write workload (recording video) which is different from the smaller writes that a running file system would cause. A similar question could be raised for performance - SD cards would be optimized for those same sequential writes, not small 4K/8K updates.

It might be a potential area where you could test - for my money, though, I would rather use an SSD and a USB adapter if I was trying to avoid consuming a valuable onboard SATA port or drive bay.

 

[Etorix]

What is the thought of the experts with the introduction of these high endurance SD cards since the last thread I saw that was from before these cards existed?

I don't think I qualify as "expert" but for what my thought is worth:
High endurance comes with high price, so what's the point of trying an unproven boot device that will cost as much as a SATADOM or several small NVMe drives, all of which are proven solutions?

 

[SubnetMask]

I don't think I qualify as "expert" but for what my thought is worth:
High endurance comes with high price, so what's the point of trying an unproven boot device that will cost as much as a SATADOM or several small NVMe drives, all of which are proven solutions?

Well, in my particular case, my FreeNAS machine is a PowerEdge FC630 - There's not a lot of real estate or connectivity inside for a DOM, NVMe or run of the mill SATA disk - only the two 2.5" bays on the one currently running FreeNAS, and eight 1.8" bays on the one I just picked up to put in place of the existing one, and all have the option for Dells internal dual SD module, which I've been using for years on quite a number of machines running VMWare ESXi with good success. I'm going down the path of adding SLOG to my setup, and those 1.8" bays are more valuable for that. The eight bays are probably more than I need for it, but in case not...

As far as 'High endurance comes with high price', they're not exactly crazy expensive. They're actually a little cheaper lol. BadBuy has the 256GB Extreme Plus listed for $39.99 and the High Endurance listed for $34.99. The 64GB High endurance is only $13.99, and spacewise, I'm pretty sure 64GB is plenty for a FreeNAS/TrueNAS boot volume.

 

[Etorix]

Well, in this case you may just be in the perfect situation to experiment with SD cards for boot! Please report.
64 GB is indeed plenty, and moving the system dataset to the HDD pool will take some wear out the flash boot device. Make sure to always have a recent copy of the configuration file at hand if the SD card fails and you need to reinstall.

 

[Patrick M. Hausen]

HP offers a "high endurance" dual SD boot device for ESXi, too. We use it for that purpose, currently. If you happen to have one from Dell at hand, I'd give it a try. The HP one is ridiculously expensive but as in your server the Microserver Gen10 Plus does not offer many options for additional boot media.

 

[Dirk]

Late to this but wanted to offer my experience. My Brutus server has a 32GB DOM that is on a PCIE adapter card and is the boot pool. It has been running 24/7 for 7 years without a burp.

 

[Griffey]

In my experience. Samsung 950 pro m.2 nvme drives work in a pciex1 lane as a boot device. I've got several in machines in x1 and x4 lanes in machines build before they existed. As they come with their own drivers they inject into the bios as "generic nvme drivers". I have 1 in my windows X58 system and my wifes X79 and several others I've sold. I'm sure for this a 256gb in a X1 slot would be perfect. As it works at normal sata speeds in pcie gen 2. It might be a bit overkill for some people. But, it's an option.